Vienna University of Technology

About: Vienna University of Technology is a education organization based out in Vienna, Austria. It is known for research contribution in the topics: Laser & Cloud computing. The organization has 16723 authors who have published 49341 publications receiving 1302168 citations.

Scaling in hydrology

Abstract: Correspondence to: G Bloschl, Institut fur Hydraulik, Gewasserkunde und Wasserwirtschaft, Technische Universitat Wien, Karrsplatz 13/223, A-1040 Wien, Austria E-mail: bloeschl@hydrotuwienacat The term ‘scaling’, to many, is veiled in a nimbus of exciting mystery At a basic level, part of the mystery simply comes from confusion of two connotations of the word—meaning either scale invariance (ie processes behaving similarly at small and large scales) or upscaling/downscaling (ie aggregating/disaggregating data) However, once this hurdle is surmounted, from whence does this excitement come and in what direction does it lead? If we follow the scale invariance track of enquiry, some hidden signature of hydrologic systems that can be encapsulated in beautifully simple equations is promised The idea of self-similarity, first conceived by L F Richardson and expertly marketed by B Mandelbrot, is compelling given so much visual evidence of variability at small and large scales And, indeed, if you believe there exists a single universal relationship underlying hydrologic processes at many scales it is hard not to fly off to cloud-cuckoo land with this idea The upscaling/downscaling track of enquiry is more practical In hydrology, much of the recent interest began in the 1970s with the early work of A Freeze and L Gelhar aggregating the groundwater flow equation based on a stochastic approach, and gained additional momentum in the 1980s when it was realized that spatial heterogeneity of the land surface matters for atmospheric models Those subdisciplines of hydrology in which the basic equations are known with some degree of confidence (eg groundwater flow) have a head start, but for catchment hydrology and hillslope hydrology there is still a long way to go before the derivation of an aggregate large-scale equation from first principles will be possible It is likely that ad hoc relationships with little theoretical justification will be with us for another few years Field hydrologists may wonder what role field observations and onsite experience have in all this, and I wonder too Is it coincidence that most of the celebrated (and rightly so) pioneers of the scaling community never were personally involved in fieldwork, or is there a causal relationship? I believe it is the latter Fieldwork and scaling theory, apparently, are too widely divergent for a single individual to excel in both Or perhaps it is something else I continue to be intrigued by the complexity of hydrological processes when in the field The rich diversity in the spatial arrangements of flow paths and mechanisms that, to the observer, quite obviously change with scale make it difficult for me, when back in the office, to write down simple formulations that neglect most of what I know is out there Many of the betterknown scaling relationships do neglect the important bits For example, stochastically averaged groundwater flow equations usually assume that

A survey on model versioning approaches

Abstract: Purpose – The purpose of this paper is to provide a feature‐based characterization of version control systems (VCSs), providing an overview about the state‐of‐the‐art of versioning systems dedicated to modeling artifacts.Design/methodology/approach – Based on a literature study of existing approaches, a description of the features of versioning systems is established. Special focus is set on three‐way merging which is an integral component of optimistic versioning. This characterization is employed on current model versioning systems, which allows the derivation of challenges in this research area.Findings – The results of the evaluation show that several challenges need to be addressed in future developments of VCSs and merging tools in order to allow the parallel development of model artifacts.Practical implications – Making model‐driven engineering (MDE) a success requires supporting the parallel development of model artifacts as is done nowadays for text‐based artifacts. Therefore, model versioning ca...